UNIVERSITY    OF   CALIFORNIA    PUBLICATIONS. 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION. 


CONTRIBUTION  TO  THE  STUDY 
OF  FERMENTATION. 

Part  I. 

By  E.  H.  TWIGHT  and  CHARLES  S.  ASH. 


Wine  Yeast  Culture. 

BULLETIN    No.    159. 

(Berkeley,  June,  1904.) 


SACRAMENTO 


w.  w.  shannon,     :     :     :     :      SUPERINTENDENT  state  printing, 

1904. 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University. 
'<'■''•■ 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist. 

E.  J.  WICKSON,  M.A.,  Horticulturist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S..  C.E.,  Irrigation  Engineer. 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.    (Soils  and  Alkali.) 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.    (Foods,  Nutrition.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.    (Starches,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.    (Fruits,   Waters,  Insecticides.) 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian,  Bacteriologist. 

E.  H.  TWIGHT,  B.Sc,  DiplomS  E.A.M.,  Viticulturist. 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

A.  V.  STUBENRAUCH,  M.S.,  Assistant  Horticulturist,  in  charge  of  Substations. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Field  Entomologist. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

H.  J.  QUAYLE,  A.B.,  Assistant  Entomologist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  Fertilizer  Coniro, 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 

C.  A.  TRIEBEL,  Ph.G.,  Assistant  in  Agricultural  Laboratory. 

C.  A.  COLMORE,  B.S.,  Clerk  to  the  Director. 


EMIL  KELLNER,  Foreman  of  Central  Station  Grounas. 

JOHN  TUOHY,  Patron,  ) 

>  Tulare  Substation,  Tulare. 
JULIUS  FORRER,  Foreman,  ) 

J.  E.  McCOMAS,  Patron,  Pomona, 

J.  W.  MILLS,  Superintendent,  Ontario,  }•  Southern  California  Substation. 

JOHN  H.  BARBER,  Assistant  Superintendent,  Ontario, 

A.  A.  KNOWLTON,  Patron, 

J.  H.  OOLEY,  Workman  in  charge, 

ROY  JONES,  Patron, 

WM.  SHUTT,  Foreman, 

H.  O.  WOODWORTH,  M.S.,  Foreman  of  Poultry  Station,  Petaluma. 


! 

tr 
y  University  Forestry  Station,  Santa  Monica. 


t  University  Forestry  Station,  Chico. 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, will  be  sent  to  any  citizen  of  the  State  on  application. 


Contribution  to  the  Study  of  Fermentation. 


By  E.  H.  TWIGHT  and  CHARLES  S.  ASH. 


The  present  bulletin  is  a  report  upon  the  cooperative  investigations 
carried  on  during  the  vintage  of  1903  by  the  Agricultural  Experiment 
Station  of  the  University  of  California  and  the  California  Wine  Asso- 
ciation of  San  Francisco.  The  Association  allowed  the  use  of  its  large 
wineries  in  Sonoma  County  and  built  a  laboratory  in  Geyserville  14  by 
14  feet  for  the  cultivation  of  pure  yeasts;  it  also  gave  the  use  of  its 
San  Francisco  laboratory  for  the  analytical  work. 

The  object  of  these  experiments  was  the  study  of:  (1)  The  influence 
of  temperature  on  fermentation;  (2)  The  influence  of  acid  (acidity  of 
must)  on  fermentation;  (3)  The  influence  of  selected  cultivated  yeasts 
on  fermentation  as  compared  with  the  natural  (wild)  yeasts;  (4)  The 
comparative  values  of  the  wines  derived  from  these  experiments. 

Considerable  work  of  this  nature  has  already  been  done  in  foreign 
countries,  principally  in  France  and  Algeria;   also  at  this  Station. 

On  the  part  of  the  California  Wine  Association,  the  observations  and 
analyses  reported  upon  in  this  bulletin  were  made  by  Charles  S.  Ash, 
who  has  charge  of  its  laboratory  and  who  divided  his  time  between  its 
wineries  in  Sonoma  County  and  its  laboratory  in  San  Francisco. 

Observations  were  made  on  360  fermentations  in  tanks  of  5,000  gallons 
capacity  each,  making  a  total  of  1,250,000  gallons  of  wine,  which  there- 
fore puts  this  work  upon  a  practical  basis — and  not  the  result  of  labora- 
tory investigation  only.  It  is  impossible,  in  a  bulletin  of  this  length, 
to  record  all  data  obtained,  so  only  the  most  characteristic  are  herein 
given. 

Effect  of  Temperature  on  Fermentation. — When  the  must  of  grapes  is 
being  transformed  into  wine,  a  chemical  change  takes  place  (C6Hi206  = 
2  C2H60  -f-  2  C02),  increasing  the  temperature.  In  the  practical  fer- 
mentation of  wine,  the  temperature  varies  from  60°  to  105°  F.  The 
most  favorable  temperature  seems  to  be  about  85°  F.  When  wine  was 
first  made  in  hot  countries,  it  was  the  ambition  of  all  the  savants  to 
produce  a  yeast  that  would  ferment  a  large  percentage  of  sugar  at  a 
high  temperature.  These  efforts,  however,  proved  to  be  of  little  or  no 
value,  for  it  was  found  that  the  higher  the  temperature  during  fermen- 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


tation,  the  greater  the  amount  of  acetic,  lactic,  and  other  acids  formed, 
and  the  lower  the  percentage  of  alcohol. 

Volatile  Acid. — Kayser,  in  France,  has  given  the  following  figures  on 
the  increase  of  volatile  acid  when  fermentation  takes  place  at  higher 
temperatures: 


25°  C.  (77°  F.). 


35*  C.  (95*  F.). 


Yeast  No.  2 
Yeast  No.  8 
Yeast  No.  9 


.0979%  Volat, 

.111.2 

.0862 


.0780%  Volat. 

.1504 

.0824 


These  figures  are  not  very  conclusive,  since  out  of  the  three  examples 
two  have  not  proven  his  statement.  We  have  experimented  very  thor- 
oughly on  the  same  lines  in  our  laboratory,  with  more  satisfactory 
results,  as  given  below: 


At  75°  F. 

At  85°  F. 

At  95°  F. 

At  102*  F. 

Yeast  No.  1 

Yeast  No.  4             .-. 

.067%  Volat. 
.071 
.059 
,  .062 

.065%  Volat. 

.073 

.059 

.061 

.097%  Volat. 

.101 

.063 

.070 

.112%  Volat. 
.119 

Yeast  No.  5 

Yeast  No.  6       .   

.094 

.100 

This  laboratory  result  was  fully  confirmed  in  two  cellars  in  Sonoma 
County,  situated  only  one  and  one  half  miles  apart,  and  handling  the 
same  quality  and  varieties  of  grapes.  We  have  designated  these  cellars 
as  "A"  and"B": 


Winery 


A". 
B" 


Average  Temperature  of 
Fermentation. 


80°  F. 
95°  to  105°  F. 


Average  Volatile  Acid. 


.078% 

.118% 


Albuminoid*. — Another  great  objection  to  fermenting  wines  at  a 
high  temperature  is  that  under  these  conditions  they  will  not  clear 
readily.  This  is  due  to  the  large  amount  of  nitrogenous  matter 
(albuminoids)  retained  in  the  wine,  and  is  exceptionally  disastrous  in 
the  ease  of  white  wines,  on  account  of  their  poverty  of  tannin.  A 
wine  with  a  large  percentage  of  albuminoids  is  also  subject  to  bacterial 
diseases. 

The  following  table  shows  the  percentage  of  nitrogen  in  wines  fer- 


CONTRIBUTION   TO   THE   STUDY   OF    FERMENTATION. 


merited  at  different  temperatures,  taken  from   Roos  and  Chabert,  two 

of   the   best   known    authorities   on   the  fermentation  of  wines  in   hot 
countries: 


Nitrogenous  Matter  in  Winks  Fermented  at: 

25°  0.  (77°  F.). 

30°  C.  (85°  F.). 

:i.V(\  (15°  F.). 

4(i°  C.  (104°  F.). 

No.  1 

No.  2 

No.  3 

.is? 

.265% 

.115 
.112 

•*22% 

.120 

.193 

.460% 
.135 

.183 

No.  4 

.205 

Alcohol. — We  now  come  to  the  most  important  factor,  from  an  eco- 
nomical standpoint,  in  the  fermentation  of  wines:  that  is,  the  amount 
of  alcohol  produced  from  a  given  amount  of  sugar.  Theoretically,  100 
parts  (100  grms.)  of  sugar  yield: 


40.00  Carbon  dioxid. 

48.40  Alcohol  (61%  by  volume  at   15°  C). 

3.20  Glycerin. 
.60  Succinic  acid. 

1.20  Used  bv  the  ferments. 


The  following  tables  on  the  above  subject  give  the  results  of  experi- 
ments conducted  in  Algeria  by  Messrs.  Roos  and  Chabert,  and  they 
demonstrate  that  there1  is  a  loss  in  alcohol  when  wine  is  fermented  at 
a  high  temperature  : 


25°  C.  (77°  F.). 


80°  C.  (85°  P.). 


35°  ('.  (95°  P.). 


40°  C.  (104°  F.). 


Must  No.    1,  17.4%  Sugar. 
Must  No.    5,  17.4%      " 
Must  No.    8,  19.0%      " 
Must  No.  11,  20.3%      " 


10.0%  Alcohol 
9.9% 
10.9%        " 


9.7%  Alcohol 

9.7%        " 
10.9%        " 
9.6% 


9.2%  Alcohol 

9.1%         " 
9.6% 

7.2% 


7.3%  Alcohol 
9.3%         " 
6.1% 


The  results  of  Messrs.  Roos  and  Chabert  are  fairly  well  confirmed* 
by  us,  the  following  experiments  having  been  conducted  in  the  labo- 
ratory  of  the  California  Wine  Association: 


*  See  Viticultural  Report  of  California  Agricultural  Experiment  Station  for  1883-84- 
85-86-87,  by  E.  W.  Hilgard. 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

Must  No.  1,  Carignane,  20%  Sugar. 


25°  C.  (77°  F.). 

30°  C.  (85°  F.). 

35°  C.  (95°  F.). 

40°  C.  (104°  F.). 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Yeast  No.  5 

Yeast  No.  6 

No  yeast  added 

11.3% 
11.2 

11.0 

.100% 

.105 

.105 

11.2% 

11.3 

11.1 

.095% 

.100 

.105 

10.8% 

10.8 

10.5 

•115% 

.105 

.180 

10.4% 

10.3 

9.9 

.200% 

.195 

.220 

Must  No.  2,  Carignane,  21%  Sugar. 

25°  C.  (77°  F.). 

30°  C.  (85°  F.). 

35°  C.  (95°  F.). 

40°  C.  (104°  F.). 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Yeast  No.  5 

Yeast  No.  6     . 

12.1% 

12.0 

11.9 

.105% 

.100 

.115 

12.1% 

12.1 

11.8 

.100% 

.105 

.120 

11.6% 

11.7 

11.4 

.215% 

.215 

.265 

10.9% 

11.2 

10.6 

.290% 
.285 

No  yeast  added 

.500 

Must  No.  3,   White,  25%  Sugar. 

25°  C.  (77*  F.). 

30°  C.  (85°  F.). 

35°  C.  (95°  F.). 

40°  C.  (104°  F.). 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Alcohol. 

Sugar. 

Yeast  No.  5. 

13.6% 
13.4 

.200% 
.210 

13.6% 
13.6 

.215% 
.200 

12.8% 
12.6 

•415% 
.450 

10.4% 
10.8 

2.10%* 
2.55* 

Yeast  No.  6 

* Stuck. 

Dryness. — And,  finally,  we  come  to  the  question  of  dryness  (low  per- 
centage of  sugar  remaining  after  first  fermentation). 

Wines  fermented  at  low  temperatures  (85c  F.  or  under)  become 
dry  very  quickly,  running  down  as  low  as  0.100  per  cent  of  sugar  within 
two  weeks,  while  wines  fermented  at  higher  temperatures  sometimes 
take  over  a  year  to  reach  this  condition.  We  consider  this  point  next 
in  importance  to  the  amount  of  alcohol  obtained,  for  upon  the  dryness 
of  a  wine  largely  depend  its  keeping  qualities.  A  glance  over  the 
table  already  given,  showing  the  amount  of  alcohol  derived  and  the 
amount  of  sugar  left  unfermented,  will  make  this  point  readily  under- 
stood. The  increase  of  unfermented  sugar  at  high  temperatures  is 
even  more  constant  than  the  increase  of  volatile  acid  under  the  same 
conditions. 


CONTRIBUTION   TO  THE  STUDY  OF   FERMENTATION. 


Summary. — Fermentation  at  low  temperatures  (85°  F.  or  under)  has 
the  following  beneficial  results : 

1.  Lower  percentage  of  volatile  acid. 

2.  Lower  percentage  of  albuminoids  (easier  to  clear). 

3.  Greater  percentage  of  alcohol  (from  1  to  2  per  cent,  according 
to  the  deviation  in  temperature  above  85°  F.,  which  appears  to  be  the 
point  of  most  perfect  fermentation). 

It  is  easy  to  recognize  the  great  losses  which  accrue  in  sweet-wine 
wineries  from  fermentation  at  high  temperatures,  especially  if  it  is  the 
ambition  of  the  wine-maker  to  ferment  them  as  rapidly  as  possible. 

4.  Dryness. 

Cooling  of  the  Must  during  Fermentation. — It  has  been  conceded  by  all 
authorities  that  cooling  the  must  is  the  only  practical  method  of  making 
good  dry  wines  in  hot  climates.  The  California  Agricultural  Experiment 
Station  at  Berkeley  in  the  season  of  1896  carried  on  very  interesting 
experiments  along  these  lines,  and  those  interested  may  find  a  detailed 


B 


A 


A,  Entrance  of  water. 

B,  Exit  of  water. 


Fig.  1.     Wine  cooler. 

C,  Entrance  of  warm  wine. 

D,  Exit  of  cooled  wine. 


E,  Plan 


account  in  Bulletin  No.  117,  "The  Control  of  the  Temperature  in  Wine 
Fermentation,"  by  A.  P.  Hayne.  The  cooler  described  in  these  experi- 
ments had  a  small  capacity,  and  though  the  results  wTere  satisfactory, 
it  did  not  come  into  general  use.  However,  one  of  these  coolers  has 
been  used  since  that  time  in  one  of  the  small  wineries  where  the  experi- 
ments were  conducted. 

The  only  argument  that  can  be  made  against  cooling  is  the  expense, 
and  that  in  very  many  instances  could  be  reduced  to  a  very  low  figure, 
amounting  to  practically  the  cost  of  pumping  the  must  through  a  coil. 

At  Geyserville  this  year  two  coolers  were  built  which  cooled  a  5000- 
gallon  tank  of  must  twenty  degrees  in  thirty -five  minutes;  cost  of  cool- 
ing estimated  at  $0.0009,  not  one  tenth  of  a  cent  per  gallon.  These 
coolers  cost  $86  apiece.  The  only  other  expense  was  the  pumping  of 
the  must  and  cold  water  through  them. 

Fig.  1  illustrates  the  contrivance  used  at  Geyserville,  which  is 
extremely  simple. 


8  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

Three  hundred  and  twenty  feet  of  1-J-inch  galvanized  pipe  were 
arranged  in  square  tiers  in  a  fermenting  tank,  each  arm  of  this  coil 
measuring  eight  feet.  The  warm  must  was  pumped  in  at  the  top  of  the 
tank  and  issued  from  the  bottom.'  The  cold  water  was  pumped  in  at 
the  bottom  and  passed  from  the  top.  It  may  be  of  interest  to  note  that 
in  this  case  it  took  about  twice  the  volume  of  water  to  cool  a  given 
amount  of  wine.     The  temperature  of  the  water  was  60°  F. 

From  our  observations  at  Geyserville,  we  found  that  after  the  must 
had  once  been  cooled,  it  fermented  out  perfectly  dry  before  the  tempera- 
ture again  had  a  chance  to  rise  to  the  danger  point. 

As  all  wineries  need  a  large  supply  of  water  for  washing  the  tanks? 
cleaning  the  machinery,  washing  the  pomace  for  brandy,  etc.,  a  cooler 
could  possibly  be  built  in  the  reservoir  from  which  the  water  is  dis- 
tributed. In  many  instances  where  wineries  are  located  alongside  of  a 
river  or  an  irrigation  canal,  the  cooler  could  be  placed  in  the  river-bed 
or  the  ditch.  In  the  building  of  new  wineries,  the  advantage  of  such 
an  acquisition  should  be  considered,  as  the  cooling  would  only  cost  the 
pumping  of  the  must  through  the  coil.  With  cheap  oil  fuel,  this  would 
be  nominal. 

Experiments  with  Cultivated  Yeasts. — Under  ordinary  conditions,  the 
transformation  of  fresh  grape  must  into  wine  is  spontaneously  pro- 
duced from  the  micro-organisms  (yeasts)  that  cover  the  surface  of  the 
grapes  at  maturity.  The  principal  factor  in  the  vinous  fermentation  is 
the  elliptic  yeast  (Saeeharomyees  ellipsoidevs).  The  natural  yeasts  of 
some  varieties  of  grapes  produced  very  much  better  fermentation  than 
others.  For  example,  in  California  the  yeasts  of  Tanat,  Burger, 
Carignane,  Mataro,  and  Alicante  Bouschet  are  very  vigorous,  while  those 
of  Mondeuse,  Malvoisie,  Zinfandel,  and  Mission  are,  as  a  rule,  quite 
feeble.  As  most  of  our  red  wines  are  made  from  Zinfandels,  our  atten- 
tion was  first  called  to  this  grape.  After  keeping  record  of  the  fermen- 
tation of  all  Zinfandels  on  natural  as  well  as  cultivated  yeasts,  we  have 
come  to  the  following  conclusion: 

Zinfandels,  when  fermented  on  their  own  yeasts  (not  mixed  with  any 
other  variety)  ferment  very  rapidly  at  first,  but  when  they  have  fer- 
mented down  to  about  2  to  5  per  cent  of  sugar,  the  temperature  of  the 
must  rises  very  high  and  fermentation  stops  for  a  period  varying  from 
a  few  hours  to  a  whole  day.  Then  (in  a  good  year,  like  1903)  they 
•become  dry.  Attached  to  this  report  are  given  some  examples  of 
typical  Zinfandel  fermentations  (Figs.  3  and  4).  The  fermentation  is 
exceptionally  irregular,  in  extreme  cases  fermenting  out  as  much  as 
12   per   cent   of  sugar  in  one  day  and  possibly  only  1  per  cent  the  next. 

In  Burgers  and  Carignanes,  the  fermentation  is  uniform  all  through 
(Figs.  6  and  7).     The  must  loses  approximately  the  same  percentage  of 


CONTRIBUTION   TO   THE  STUDY  OF  FERMENTATION.  iJ 

sugar  the  third  as  the  second  day,  and  so  on  until  the  fermentation  is 
finished;  or  they  ferment  the  greatest  amount  of  sugar  the  second  day 
and  gradually  decrease.  This  is  the  reason  why  wine-makers  like  to 
mix  Carignanes  (or  Burgers)  with  Zinfandels  (Figs.  11,  12,  13). 


Previous  to  the  vintage,  we  pursued  the  following  plan:  A  great 
many  varieties  of  yeasts  were  experimented  with,  pure  cultures  of  all 
first  being  made.  These  pure  cultures  were  obtained  by  starting  from 
one  cell.  After  they  were  made  they  were  tested  in  the  same  medium 
and  under  different  conditions  in  order  to  select  the  most  vigorous. 
Our  work  was  carried  on  with  two  of  these  selected  yeasts,  which  we 
have  designated  as  No.  5  and  No.  6. 

The  inoculations  from  the  pure  cultures  were  made  into  test-tubes 
full  of  sterilized  must;  then  from  the  test-tubes  into  quart  flasks  three- 
fourths  full  of  sterilized  must;  from  the  flasks  into  10-gallon  kegs 
three-fourths  full  of  sterilized  must;  and  finally  into  50-gallon  barrels 
three-fourths  full  of  sterilized  must.  The  transfer  from  the  smaller  to 
the  larger  vessel  was  made  only  when  the  fermentation  was  in  full 
swing.  In  making  these  transfers,  the  greatest  care  was  taken  to  guard 
against  contamination,  the  casks,  bungs,  bungholes,  etc.,  being  sterilized 
with  steam.  When  the  must  in  the  barrel  was  at  its  highest  ferment- 
ing activity,  it  was  dumped  into  one  of  the  regular  fermenting  tanks 
containing  freshly-crushed  grapes. 

For  each  fermenting  tank  to  which  cultivated  yeast  had  been  added, 
we  filled  another  tank  with  the  same  variety  of  must  and  the  same 
percentage  of  sugar,  but  fermenting  by  its  own  natural  yeast,  to  serve 
as  a  check.  The  fermentation  of  both  tanks  was  recorded  and  an 
account  kept  of  the  amount  of  sugar  lost  each  day,  the  height  of  the 
temperature  developed,  etc.  Some  of  these  records  are  embodied  in 
this  bulletin  along  with  the  analyses  of  the  wines  fermented  with  both 
natural  and  cultivated  yeasts,  showing  gain  (or  loss)  of  the  wines  fer- 
mented with  cultivated  yeasts  over  those  fermented  with  the  natural  as 
regards  percentages  of  alcohol,  volatile  acid,  and  unfermented  sugar 
obtained.  As  there  were  some  three  hundred  records  taken,  it  would 
be  impossible  to  discuss  them  all,  so  only  the  most  typical  are  given. 


10 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


DISCUSSION    OF   CHARTS. 

Fig.  2  shows  an  ideal  fermentation;  represented  as  the  diagonal 
of  a  rectangle.  The  figures  on  one  side  of  the  diagonal  represent  the 
temperatures,  and  on  the  other  the  percentages  of  sugar  in  the  must. 
In  this  diagram  the  time  that  has  elapsed  between  the  tilling  of  the 
tank  with  must  and  the  completion  of  the  fermentation  is  four  days. 

Temperature. 


69   70   71    72  73  74   75    76   77  78  76  60  81    82    83  84    85  88  8  7   68 

24 

23 
22 

21 
20 

i  e 

1  8 
I  7 
1  6 
1  6 

1   4 

I  5 
1  2 

1  1 

)  0 

9 

a 

7 
6 

S 

4 

5 
2 

0 

\ 

\ 

V 

\ 

k 

\ 

\ 

f'Vty 

v 

\ 

\ 

s 

v 

\ 

V 

5nc1 

day 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\3" 

day 

\ 

\ 

\ 

\ 

\ 

x 

\ 

4""'day 

Fig.  2.     Diagram  showing  ideal  fermentation. 


CONTRIBUTION  TO  THE  STUDY  OF  FERMENTATION. 


11 


Temperature. 


70   71    727374    75    76   77  7*768081    82    85  84    858887   88  89  90    91 

25 
24 

25 
22 

21 
20 

i  ei 

1  8 
i  7\ 
l  6 
I  B| 
I  4 
1  5 
1  2 
]  1 
1  0 
© 

e 

7 
6 
5 

4 
5 
2 

1 
0 

bep 

.irtt      l?"iUl 

IT 

1  s 

s. 

3 

16"^  m 

\ 

n,H 

am 

\ 

^'"pm 

\ 

i  N 

s 

\ 

s 

X 

\ 

/\  H^a  m 

\ 

S 

1 

r 

\ 

s 

\  \3"'am 

/ 

V 

'* '"  T>  ™ 

\ 

\ 

/ 

\ 

s 

\ 

\j 

\ 

s 

s 

\ 

•n^pm 

N 

V 

19'  p.m 

\ 

i9'hdm 

s 

s 

S^I9,HpTn 

N 

s 

«H 

a-w 

S 

\£ 

> 

zo* 

£$1 

> 

*On 

pm 

^ 

,2isfam 

\ 

If 

p  m 

,^"rf 

Am 

if 

p.m 

v 

^ 

vSi'^jn 

■JZ"" 

p.m 

r'.i 

^rtu 

23,,Jam. 

Fig.  3.     Typical  Zinfandel  fermentations,  showing  great  irregularity. 

The  curves  in  Fig.  3  show  typical  Zinfandel  fermentations.  It  can  be 
seen  that  the  fermentation  of  this  variety  of  grape  is  very  irregular, 
especially  at  the  end,  as  previously  mentioned  (see  p.  8).  Note  that 
on  the  17th  of  September,  p.  m.,  the  percentage  of  sugar  in  the  must 
was  only  10,  and  on  the  18th  a.  m.,  the  next  morning,  it  had  again 
risen  to  15  per  cent.  This  is  not  an  uncommon  occurrence,  for  it  occa- 
sionally happens  that  there  are  dried  grapes  (raisins)  among  the  bunches 
that  are  delivered,  and  when  the  fermentation  sIoavs,  the  sugar  in  the 
raisins  has  time  to  dissolve.  This  condition  is  a  serious  obstacle  to  the 
wine-maker,  especially  when  the  percentage  of  raisins  is  large,  as  was 
the  case  in  the  vintages  1900  and  1901.  The  same  condition  is  repre- 
sented on  Fig.  4. 


12 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 


Temperature. 


70   71    72  73  74    75    76   77  78  79  60  81    82    63  64    85  86  8  7   68  89  90    91 

25 
24 
23 
22 

III 
2  0; 

ie| 

1  6, 

«*| 
1  6 
15 

n| 

1  3 
I  2 
1  t 
A  0 

e 

8 
7 
6 
5 

4 
3 
2 

1 
0 

\ 

Sept 

.l6"V»m 

/ 

/ 

/ 

17" 

am 
A 

/ 

i? 

*&* 

// 

s 

rib"ym\ 

n" 

p  in 

\ 

\ 

V 

\ 

\ 

id^m 

\ 

s 

\ 

V 

la1* 

i  m 

"\-t'a"pni 

X 

\ 

J 

\ 

\ 

^N 

s 

18'" 

pm 

V 

i9"cim 

Si9"fm 

20* 

am 

\ 

f 

A.« 

\ 

20* 

pin 

V 

*N 

k 

nm 

21" 

7^ 

K"a? 

2l" 

p  m 

/|  m,« 

pin 

Fig.  4.  The  irregular  line  starting  September  16th  shows 
typical  irregular  Zinfandel  fermentation. 

The  straighter  line  starting  September  17th  shows  that  of 
second  crop. 

In  Fig.  4  the  irregular  line  starting  September  16th  shows  a  typical 
first-crop  Zinfandel  fermentation;  the  straighter  line  that  of  a  second- 
crop.  Note  the  great  improvement  in  fermentation  in  the  latter,  the 
line  showing  the  reduction  of  the  sugar  being  nearly  straight  while  14 
per  cent  is  being  fermented  out.  This  improvement  is  due  largely  to 
the  natural  higher  acidity  of  second-crop  grapes  (see  p.  25). 


CONTRIBUTION  TO  THE  STUDY  OF  FERMENTATION. 


13 


Temperature. 


70    71     72   73   74    75    76   77  78  79  60  8  t    82    83  84    85  88  8  7    88  89  90    9! 

25 
24 

23 
2  2 
2  1 

20 
1  9 
I  8 
i  7 
1  6 
1  5 
1  A 
1  3 
1  2 
1   1 
1  0 

e 

8 
7 
6 
5 

A 

5 
2 

0 

Sept 

2  7"VlT71 

> 

\ 

V 

V 

\ 

s, 

\ 

i 
I 

N 

\ 

\ 

W^dm 

\ 

\ 

\23""  pm 

S 

r 

0*p.m 

30" 

pm 

Fig.  5.    Zinfandel  and  Carignane  fermentation. 

Fig.  5  shows  how  the  fermentation  of  Zinfandel  grapes  is  improved 
by  mixing  a  certain  proportion  of  grapes  of  a  variety  known  to  ferment 
well  (Carignane,  in  this  instance). 


14 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


Temperature. 


71    72  75  74   75   76  77  7«  78  80  8  1    82   85  84   85  88  8  7   88  89  60    91    92 

24 

25 
22 
2  I 

2  0: 
IGt 

!  8, 
1  7| 
I  6 

1  si 

1  4 

I  S| 

!  2 

1  1 

)  0 

9 

8 

7 

8 

5 

4 

5 
2 

0 

Vnt 

25" 

pm 

\ 

\ 

J 

<0ct6'\\m 

\ 

u^ 

^ 

\ 

V    > 

X 

r 

r< 

x 

^26^  m. 

\ 

\ 

\s8~am 

S.  26npm 

\ 

^ 

\, 

s> 

\ 

\- 

-^-p. 

\ 

\ 

\ 

\ 

\ 

\ 

Sff 

\ 

\ 

\ 

\ 

\ 

\ 

s 

X- 

\ 

\ 

\9"«  m 

v 

8"  a 

£ 

\ 

Vf,. 

\9'"p.n\ 

Fig.  6.    Typical  Carignane  fermentations. 

The  good  fermenting  quality  of  the  Carignane  is  shown  in  Fig.  6,  the 
fermentation  being  through  in  three  days  without  very  great  increase 
in  temperature  in  one  instance,  and  in  three  and  one  half  days  in  the 
other.     Note  the  regularity  in  loss  of  sugar. 


CONTRIBUTION  TO  THE  STUDY  OF  FERMENTATION. 


15 


Temperature. 


75   76  77  78  78  60  8  1    82    65  64    85  86  6  7   68  80  90    91    92  95   94   95   96 

23 
22 
21 
2  0' 
19 
18, 
"1 
16| 
1  5 
1  4 
1  3 
1  2 
1   1 
1  0 

e 

8 
7 
6 
5 

4 
3 
2 

1 
0 

Oct 

^i^m 

\ 

i 

"rim 

V 

s\ 

KiS"pm 

r> 

I6"rim 

Ss 

Vl6'*cHH  N 

\ 

\ 

> 

V 

s 

N 

N 

X 

r_ 

\ 

nVtiN.  |  \ 

1.7'Am 

Fig.  7.     Typical  Burger  fermentations. 

Typical  Burger*  fermentations  are  shown  in  Fig.  7.  Burger  is 
invariably  very  regular.  The  must  of  this  variety  seldom  has  over 
22  per  cent  in  sugar,  while  the  accidity  remains  high  (.5  to  .9).  Such 
a  composition  is  very  favorable  to  a  good  fermentation  (see  p.  25). 
Burger  yeast,  however,  has  a  good  deal  to  do  with  the  above  regularity, 
as  will  be  shown  later  by  some  experiments  that  are  being  conducted 
at  present. 


*It  must  be  remembered  that  the  grape  called  Burger  in  California  is  not  the  true 
Burger  of  the  northern  grape  belt  of  Europe.  Its  true  origin  has  net  been  definitely 
determined.    (See  Viticultural  Report  for  1896,  p.  244.) 


16 


UNIVERSITY  OP  CALIFORNIA— EXPERIMENT  STATION. 


The  following  examples  show  the  comparative  fermentation  of  Zin- 
fandel  with  its  own  yeast  and  Zinfandel  with  cultivated  yeast,  the  must 
in  both  tanks  being  identical.  Out  of  the  nine  examples  given,  seven 
show  a  gain  in  favor  of  the  tank  fermented  with  pure  cultivated  yeast 
as  a  starter.  The  other  two  are  equal  to  the  natural  fermentation. 
The  natural  yeast  is  represented  by  a  solid  line;  the  cultivated  yeast 
by  a  dotted  line. 

Temperature. 


80  81  6263  9466  S6  674869   70   71    72  73  74   75   76   77  76^79  80  8  1    62    65  64    85  86 

24 

25 
22 
21 

20: 
i  9 

'8; 

l» 

16 

16! 
1  4 
1  3 
1  2 
1  1 
1  0 
0 

e 
7 
6 
5 

4 
5 
2 

"0 

Sepl 

\\&nnm 

^v 

pm. 

A 

X 

^  ?0M  o.m 

18" 

P"\ 

\ 
is 

"Am 

Strain 

\ 

IS" 

a  m 

\ 

s 

>" 

'ifm 

■s 

I 

^N 

/ 

x 

/ 

x. 

M*1»*_ 

Jv 

'pm 

N 

^lk~"?m 

ZO" 

am 

\ 

\ 

^, 

\ 

N   v 

\ 

;o'* 

n  m 

^*3"V»m 

- 

-Ty*J™ 

- 

X 

^ 

'-> 

X 

N. 

Tl 

^ 

■  1 

__ 

24" 

pm 

< 

(s2l,T,p 

2  5" 

a  m 

\ 

|    Sm1i« 

Fig.  8.    Natural  Zinfandel  fermentation  (solid  line)  and  fermentation 
with  pure  yeast  (dotted  line). 


Sugar  fermented  1st  day 

2d  "  

3d  "  

4th  "  

5th  "  

6th  "  

6}  "  -- 

Completed  in 6|  days 


Natural 

With  Pure 

Fermentation. 

Yeast. 

o% 

4% 

1 

7 

7 

7 

3 

4 

5 

.- 

5 

__ 

1 

__ 

4  dav 


In  the  fermentation  shown  in  Fig.  8  the  tank  with  cultivated  yeast 
was  dry  two  and  a  half  days  before  the  tank  fermenting  on  its  natural 
yeast,  the  regularity  of  fermentation  being  nearly  perfect  in  the  tank 
with  cultivated  yeast. 


CONTRIBUTION    TO    THE    STUDY    OF    FERMENTATION. 


17 


Temperature. 


70   71    72  73  74    75    76   77  78  76  80  81    82    63  84    85  86  8  7    88  86  90    91     92  93 

24 

23 
22 

21 

20 
10 

1  8' 

1*1 
1  6 
1  5 
1  4 
1  3 
1  2 
1  1 
1  0 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

1 

5epr) 

«i,J8*&m. 

Il£ 

"V*nT»ff)JTi 

1 — 1 

7*l^v 

20*0" 

^TS^m 

r 

*> 

s 

/ 

/x 

/ 

s 

/ 

N 

/ 

N. 

s 

/ 

s 

s 

/ 

V 

19" 

Am 

I 

v 

*> 

[z£%™ 

"> 

-^ 

2  2"^™ 

s 

Id^jm. 

v- 

>Jfl> 

\ 

Sent  to 

Cooler 

S 

\ 

2  3' 

iJ]L 

t^X 

>i 

24'^ 

io*^  m 

^ — 

>2S'dm 

^  20,>lp. 

' 

-' 

*^6",am 

'Xl'Vim 

Fig.  9.    Natural  Zinfandel  fermentation  (solid  line);  the  same 
with  pure  yeast  (dotted  line). 


Sugar  fermented  1st  day 
2d 


3d 
4th 
5th 
6th 
7th 
"  8th,  9th 
Completed  in 


Natural 

With  Pure 

-mentation 

Yeast. 

1% 

2% 

1 

11 

1 

6 

1 

4 

10 

1 

4 

_. 

4 

„, 

9  days 

4  days 

This  chart  (Fig.  9)  also  shows  a  gain  of  five  days  in  favor  of  the 
tank  with  cultivated  yeast,  the  regularity  of  fermentation  being  also  in 
its  favor.  The  apparent  irregularity  in  the  dotted  line  representing 
the  pure  cultivated  yeast  fermentation  on  the  19th  p.  m.  was  due  to  the 
must  in  the  tank  being  sent  through  the  cooler. 


18 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


Temperature. 


6  6  66   676668   70   71    727374   75    76   77  76^768081    82   83  64   85  8687   68  86  6091 

24 
23 
22 
t| 

2  0; 

!  6 

i  e; 

i 7; 

1  6 
16 

1   4 

1  3 

I  2 

1  1 

1  0 

0 

8 

7 

6 

6 

« 

5 

2 

0 

If 

3epl[ 

J3**,*  m 

i 

'"a  m 

\ 

"1^3  "p  m 

' 

s 

| 

14'" 

i4"pin%N. 

ii  j  i      j 
i  i  i  i  i 

s  . 

SiV^'k 

i  '         ' 

"    sj\ 

1      1      1      1      1      1 

i5'"amN 

v\'*"'pm 

L 

s 

II  1  1  II 

!       1       ! 

JTU« 

rn 

! 

s 

\ 

~ 

i 

v 

\ 

1 
1      | 

"-!xi6'>m       | 

\l5'"^fTl 

i 

Ml 

S 

s 

1    I 

1       : 

s 

>'?'> 

'vi7-*m 

A 

it 

^ 

p 

A 

,7>> 

Si7'am 

H 

/i7"pTn 

fi8"am 

/    J 

il 

n8"'am 

•i8B,pm 

Fig.  10.     Natural  fermentation  of  Zinfandel  (solid  line),  and  with 
pure  yeast  (dotted  line). 


Sugar  fermented  1st  day. 
2d    "    . 


3d 
4th 
5th 
6th 


Natural 

With  Pure 

Fermentation. 

Yeast. 

6% 

3% 

8 

5 

4 

5 

1 

3 

3 

4 

._ 

2 

5  days 

5$  days 

Completed  in 5  days 

In  this  instance  (Fig.  10),  the  natural  fermentation  was  more 
rapid,  being  a  half  day  in  advance  of  the  tank  with  the  cultivated 
yeast;  but  the  natural  fermentation  is  quite  irregular  toward  the  end. 


CONTRIBUTION    TO    THE    STUDY    OF    FERMENTATION. 


19 


Temperature 


70  71 

72  73  74    75    76   77  7876   80   8  1    82    83  64    85  88  8  7    88  86  90    61     92   93   94    95   96  97  98 

24 
23 
22 

21 

20 

i  e 

1  8 

17 
1  6 
1  6 
1  A 

1  3 
1  2 

1  1 
1  0 

e 

8 
7 
6 
5 
4 
3 
2 
1 
0 

1 

kfl 

— 

Jf 

"p.m 

19 

>pm 

^ 

Ei"p.m 

.  p 

ZZ"km/ 

1 — 

kzo""*!!! 

^~      ,     - 

1 

N 

!    1   1   • 

L20"'ATTifrp  nv 

X 

\ 

"" 

-* 

^ 

'kwSpm 

> 

sv2  2.-"'pm 

i    ;   !   i   •■   ■ 

H'fiH, 

In. 

v^i'^pm      > 

\ 

| 

I 

23* 

l.«f» 

v^JS/'aJn. 

, 

> 

. 

I   i 

1 

~~ 

-.23"^™ 

| 

"*« 

-j?r 

m\ 

] 

nn 

i 

i 

1 

•      •[ 

V    > 

\  24'Vm 

! 

_Jj 

r      1 

i 

\|        | 

1.       J 

\^24>ir 

24'"d.m\ 

u  r\ 

\  25'" 

IE 

»*a  |g 

Fig.  11.     Natural  fermentation  of  Zinfandel  and  Carignane,  mixed  (solid 
line);  the  same  fermented  with  pure  yeast  (dotted  line). 


Sugar 

fermented  1st  day 

" 

2d     " 

" 

3d    " 

<< 

4th  " 

a 

5th  " 

u 

5|     '* 

" 

(>th  " 

Natural 

With  Pure 

Fermentation. 

Yeast. 

2% 

4% 

1 

1 

5 

3 

5 

4 

8 

6 

3 

__ 

._ 

4 

5£days 

6  days 

Completed  in 5^  days 

The  result  shown  in  Fig.  11  does  not  bring  out  much  difference 
between  the  two  fermentations.  The  tank  with  the  cultivated  yeast  is 
half  a  day  behind,  but  more  regular  in  the  reduction  of  the  sugar  toward 
the  end.  Notice  that  in  this  case  there  is  a  mixture  of  Zinfandel  and 
Carignane. 


20 


UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 


Temperature 


70   71    72  75  74    75    76    77  7879  60  8  1    82    65  64    85  88  8  7   88  89  90    91 

24 
25 
22 

2  1 
20 
1  9 

i  e 

1  7 
1  6 
i  5 
I  4 

l  ; 

1  2 

1  1 

1  0 
9 
9 
7 
6 
5 

4 

5 
2 

) 
0 

p  m 

23"am 

1 

-N23"'pm 

W- 

^ 

2  4  "am 

"V 

\ 

^ 

-" 

\ 

v24**pm 

\ 

\ 

\ 

N 

■^25'am 

/ 

N 

• 

/ 

25'a^y 

' 

/ 

^ 

/ 

\ 

/ 

/ 

N 

/25">  m 

^.25"'pm 

\ 

, 

- 

K 

\ 

< 

26"A  m 

26"<vrcN> 

v 

k. 

^Z6> 

~- 

■"  >,  26'"  pnt 

Fig.  12.     Natural  fermentation  Zinfandel  and  Carignane,  mixed  (solid 
line) ;    with  pure  yeast  (dotted  line). 


Sugar  fermented  1st  day 
2d  "* 
3d     " 

Completed  in 


Natural 

With  Pure 

Fermentation. 

Yeast. 

2% 

5% 

8 

7 

11 

8 

2 

2 

3£  days 

3£  days 

Here,  as  shown  in  Fig-.  12,  there  is  also  a  mixture  of  Zinfandel  and 
Carignane,  and  the  fermentation  lasts  three  and  one  half  days  in  both 
tanks;  but  the  tank  with  the  eultivated  yeast  is  far  more  regular. 


CONTRIBUTION    TO    THE    STUDY    OF    FERMENTATION, 


21 


Temperature. 


72  73  74 

75   76   77  78- 79  80  81    82    83  64   85  88  8  7   88  69  90    91     92  »3  94   95   96  97  98  99 

24 
23 
22 

2  r 

20 

101 
1  8, 

1*1 

16! 

is; 

14 

1  3 
!  2 
1  1 
]  0 

0 

8 

7 

6 

5 

3 
2 

1 
0 

5ept[ 

ij6,hd 

n. 

20'cUn 

— - 

--" 

t 

V 

VTjyi 

pm 

l< 

O'Ym. 

\ 

\ 

\ 

^I> 

\ 

M'lun. 

l£2"?im 

\ 

"*"* 

-^ 

\ 

\ 

** 

** 

,\ 

\ 

V 

\ 

- 

•^ 

^ 

2""p  in 

N 

N 

\ 

\ 

V 

ksZ?"V*m 

23"" 

pm 

Zi" 

a.m 

\ 

v 

\ 

X^^'^m. 

ZS* 

pm 

\ 

\Z4"1 

pm. 

\ 

V 

\ 

JS'^am 

~>24""am. 

1 

„'• 

[) 

I5'\m. 

•24"pm 

^"pmj 

Fig.  13.     The  solid  line  shows  natural  fermentation  of  Zinfandel  and  Carig- 
nane ;  the  dotted  line  shows  same  fermented  with  pure  yeast. 


Sugar  fermented  1st  day. 
2d    "    . 


Con 


3d 

4th 

4| 

5th 
6th 


pleted  in 


Natural 

With  Pure 

Fermentation. 

Yeast. 

0% 

2% 

9 

2 

3 

9 

4 

6 

._ 

2 

4 

_•_ 

1 

__ 

6  days 

■ih  days 

In  this  fermentation  of  Zinfandel  and  Carignane,  mixed  (Fig.  13), 
the  pure  yeast  has  gained  half  a  day  on  the  natural  yeast  and  is  also 
more  regular. 


22 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


Temperature. 


80   81   82  83   8465   66    87   9869    70    71    72   737475    76    77   7879   80   81    82    83   8  4    85   8887    88  89 

24 

23 
22 

2  || 
20 

]  g 

i  8 
l  7 
1  6 

i  s 

i    4 
I  3 

:  2 
;  1 
1  0 
9 
3 
7 
6 
5 
4 
5 
2 

5 

V-jn 

2  9'"pm 

29'^m 

1 

30' 

,,_ 

/     1 

rf3fl 

"^m 

/    1 

M<] 

**•  £ 

— 

?*m~ 

~^ 

__ 

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~ 

'*> 

w> 

pN! 

\ 

X 

\ 

SL 

s 

s 

Sn 

3"am 

! 

\s$."*d  m 

1 

i 

. 

\\ 

1 

s 

1 

W'r 

1       1        '        1 

i'* 

?mV 

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i       1 

i  i  i 

V 

■>«> 

\  y^  m 

I 

7n^ 

"^v- 

\ 

V 

I-  II 

4^>\ 

l"1 

Fig.  14.     Natural  fermentation  of  Carignane  and  Malvoisie,  mixed  (solid  line); 
with  pure  yeast  (dotted  line). 


Sugar  fermented  1st  day. 
2d    "    . 


3d 

4th 

5th 


Completed  in 


Natural 
Fermentation. 

2°/ 
2 

With  Pure 
Yeast. 

1% 
2 

4 

9 

7 

5 

5  days 

6 

3 

5  days 

The  fermentation  of  a  mixture  of  Carignane  and  Malvoisie  is  shown 
in  Fig.  14.  The  good  fermenting  quality  of  the  Carignane  shows  in  the 
regularity  of  the  fermentation  under  natural  conditions.  There  is, 
however,  a  slight  gain  of  half  a  day  in  favor  of  the  cultivated  yeast. 


CONTRIBUTION    TO    THE    STUDY    OF    FERMENTATION. 


23 


Temperature. 


53  9465  86    97  8969   70   7|    727374    75    79   77  78798081    82    63  64    85  898788  89  90    91    9J 

24 

23 
22 
2  1 
20 
1  9 
1  8 

1   7 

1  6 

1  5 

1  4 

1  3 

1  2 

)   1 

1  0 

9 

9 

7 

« 

5 

■4 

3 

2 

1 

0 

5ept  JO'M  m 

3o*Kpm 

J  Jo"^'  m 

r 

1  3o**  p  m 

> 

\ 

Octi'Vm^ 

^ 

^s 

s 

in" 

a  in 

\ 

\ 

^""a 

m 

\ 

N  , 

"NJ^ptl 

I  j 

\ 

1  1 

. 

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!   ! 

I 

f\ 

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| 

r~7 

3" 

am 

- 

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i  ! 

t 

V- 

y  pm 

i 

V 

1 

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#>3"«piJ\i 

i 

/ 

\ 

/'-♦"•pm. 

^pjN 

Fio.  15.     Natural  fermentation  of  Carignane  and  Malvoisie,  mixed  (solid  line): 
the  same  fermented  with  pure  yeast  (dotted  line). 


.Sugar  fermented  1st  day 

2d 

3d 

4th 

4i 

5th 
Completed  in 4|  days 


Natural 

With  Pure 

ermentation 

Yeast. 

2% 

3°/ 

1 

3 

6 

6 

8 

£ 

5 

._ 

._ 

2 

4|  days 

b\  days 

The  results  in  these  two  tanks  of  Carignane  and  Malvoisie,  mixed 
(Fig.  15),  were  identical,  both  fermentations  finishing  at  the  same  time. 


24 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


Temperature. 


70   7|    72  73  7«   75   76   77  78  7©  80  8  1    82    83  84   85  86  8  7   88  89  90    61    92  93,94 

24 
25 

22 
21 
20 
I  8 

1  8. 
1  7, 
1  6 
1  5 
1  4 
1  3 
1  2 
!   1 
10 
9 

e 

7 
6 
5 

4 

5 
2 
1 
0 

Oct 

r 

5  "Vim 

U 

"VllTl 

i5'"pm. 

"1 

-fits 

I5'fcpnr»> 

\ 

N 

s 

V 

V 

\ 

s. 

s 

i6'a 

m  s 

k 

K 

N 

X 

k 

16'"  pm 

x 

\ 

N  N 

x  v 

s, 

7  "am. 

N 

l6'"pm 

1 

\ 

l7"r 

) 

V 

\ 

< 

\ 

18'"^  m. 

N 

\ 

I7"dm1 

l9"rtTTl 

; 

^ 

H» 

Fig.  16.    Natural  fermentation  of  Mataro  and  Carignane,  mixed 
(solid  line);   same  fermented  with  pure  yeast  (dotted  line). 


Sugar  fermented  1st  day 
2d    " 


3d 

4th 

4£ 


Completed  in 


Natural 
Fermentation. 

1% 
3 

With  Pure 
Yeast. 

3% 
6 

7 
5 

11 
2 

4 
4£  days 

3  days 

With  two  varieties,  such  as  Mataro  and  Carignane,  that  ferment  well 
(Fig.  16),  we  have  a  regular  and  rapid  fermentation,  but  the  tank  with 
the  cultivated  yeast  is  much  more  regular  and  one  and  one  half  days 
ahead. 


CONTRIBUTION    TO    THE    STUDY    OF    FERMENTATION. 


25 


Analyses  of  Wines  resulting  from  Various  Fermentations  Recorded  on 
Charts. — From  an  observation  of  the  analyses  of  the  wines  resulting 
from  the  fermentations  recorded  on  Figs.  8,  9,  10,  11,  12,  and  13, 
it  will  be  seen  that  the  percentage  of  alcohol  in  the  wines  fermented 
with  cultivated  yeast  is  either  greater  than  or  about  the  same  (with 
the  exception  of  No.  13)  as  in  the  wines  fermented  on  their  natural 
yeasts.  The  volatile  acid  and  the  percentage  of  unfermented  sugar 
are  in  all  cases  lower  in  the  wines  fermented  on  cultivated  yeast. 

Analyses  of  Wines  resulting  from  Fermentation  with  or  without  Addition  of  Cultivated  Yeast. 

Corresponding  to  Charts. 


Chart  No. 

Tank  No. 

Fermentation. 

Alcohol. 
Per  Cent  by  Volume. 

Volatile  Acid. 
Grs.  per  100  c.c. 

Reducing  Sugar. 
Grs.  per  100  c.c. 

*     1 

314 
294 

Natural 
Yeast  No.  6 

12.0 
12.3 

.084 
-.065 

.265 
.090 

9     1 

292 
291 

Natural 
Yeast  No.  6 

10.9 
10.9 

.133 

.052 

.110 
.075 

10        ) 

173 
272 

Natural 
Yeast  No.  5 

11.9 
11.8 

.096 

.080 

.205 
.100 

a  1 

307 

177 

Natural 
Yeast  No.  5 

12.3 

11.8 

.094 
.080 

.170 
.120 

12        j 

307 
313 

Natural 
Yeast  No.  5 

12.3 
12.3 

.094 
.085 

.170 
.110 

13        ] 

172 
171 

Natural 
Yeast  No.  6 

11.9 
12.4 

.096 
.093 

.205 
.175 

Correction  of  the  Acidity  of  the  Must. — It  has  frequently  been  stated 
that  when  the  must  is  deficient  in  free  acid,  the  fermentation  is  slower, 
and  sometimes  the  wine  does  not  pull  through.  Roos  and  Chabert, 
Bouffard,  Casalis,  and  Coste-Floret  in  France  are  among  the  authori- 
ties who  have  demonstrated  the  importance  of  correcting  the  acidity  of 
the  vintage.  It  appears  that  0.7  to  0.8  per  cent  is  about  the  normal 
amount  of  acidity  needed  in  the  fermentation  of  dry  red  wine.  When 
the  acidity  falls  below,  it  is  a  common  practice  in  Italy  and  France  to 
raise  the  acid  strength  to  this  standard  by  adding  tartaric  acid  to  the 
crushed  grapes.  This  is  considered  a  lawful  operation,  for  if  the  addi- 
tion be  properly  made,  it  does  not  add  anything  to  the  wine  that  would 
be  injurious  to  health,  nor  does  it  increase  the  volume;  most  of  the  acid 
is  precipitated  with  the  lees. 

During  the  vintage  we  made  numerous  investigations  on  the  effect  of 
various  percentages  of  acidity  on  the  fermentation  of  must,  and  clearly 
demonstrated  that  when  the  acidity  was  deficient,  the  fermentation  suf- 
fered. In  such  cases  we  increased  the  acidity  to  the  European  standard, 
with  good  results.  Different  varieties  of  grapes  need  different  acidi- 
ties, but  probably  0.65  to  0.75  per  cent  for  white  grapes  and  0.70  to  0.80 


26  UNIVERSITY    OF   CALIFORNIA EXPERIMENT    STATION. 

per  cent  for  reds  is  sufficient  for  California  wine.  We  expect  to  con- 
tinue this  investigation,  with  experimental  data,  this  coining  vintage. 
(See  Figs.  4  and  7.) 

The  Addition  of  Sulfurous  Acid  or  Sulfites  to  White  Wine. — We  made 
some  investigations  on  the  principle  of  Andrieu  for  the  handling  of 
white  grapes.  His  theory  is  to  stop  the  natural  fermentation  of  the 
must  by  adding  sulfurous  acid  (sulfur  fumes  or  a  metallic  sulfite). 
The  fermentation  being  checked  for  a  period  of  from  twenty-four  to 
forty-eight  hours,  the  dirt  settles  and  a  comparatively  clean  must  can 
be  drawn  off.  The  clean  must  is  then  inoculated  with  a  pure  cultivated 
yeast  trained  to  ferment  in  the  presence  of  as  great  or  a  greater 
percentage  of  sulfurous  acid  than  has  been  added  to  the  must.  The 
advantage  of  this  method  is  supposed  to  be  the  improvement  of  the 
wine,  as  it  is  fermented  in  a  comparatively  clean  state.  Very  satis- 
factory results  have  been  obtained  by  this  method  in  the  treatment  of 
grapes  that  have  been  damaged  by  mildew  or  early  rains. 

We  have  not  sufficient  data  to  offer  any  conclusions  this  year,  but 
the  method  seems  very  promising.  Further  investigations  will  be  made 
the  coming  vintage. 

Points  Noted  on  Comparison  of  Fermentations  with  and  without  Culti- 
vated Yeasts. — 1.  Fermentation  with  cultivated  yeasts  is  more  regular. 

2.  Start  of  fermentation  with  cultivated  yeasts  is  more  rapid. 

3.  Period  of  fermentation  is  about  the  same  in  both. 

4.  Temperature  is  the  same. 

5.  The  correction  of  the  acidity  in  the  must  to  0.7  or  0.8  per  cent 
with  tartaric  acid  greatly  assists  the  fermentation  of  dry  wines. 


REPORTS   AND  BULLETINS  AVAILABLE  FOR  DISTRIBUTION, 


REPORTS. 

1896.  Report    of    the    Viticultural    Work    during    the    seasons    1887-9'],    with    data 

regarding  the  Vintages  of  1894-95. 

1897.  Resistant   Vines,    their    Selection,   Adaptation,   and    Grafting.      Appendix   to 

Viticultural  Report  for  1896. 

1898.  Partial  Report  of  Work  of  Agricultural   Experiment  Station  for  the  years 

1895-96  and  1896-97. 
1900.     Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 
1902.     Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

BULLETINS. 
No.  121.     The  Conservation  of  Soil  Moisture  and  Economy  in  the  Use  of  Irrigation 
125.     Australian   Saltbush.  [Water. 

127.  Bench-Grafting  Resistant  Vines. 

128.  Nature,  Value,  and  Utilization  of  Alkali  Lands. 

129.  Report  of  the  Condition  of  Olive  Culture  in  California. 

131.  The  Phylloxera  of  the  Vine. 

132.  Feeding  of  Farm  Animals. 

133.  Tolerance  of  Alkali  by  Various  Cultures. 

134.  Report  of  Condition  of  Vineyards  in  Portions  of  Santa  Clara  Valley. 

135.  The  Potato- Worm  in  California. 

136.  Erinose  of  the  Vine. 

137.  Pickling  Ripe  and  Green  Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange  and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Robles. 

142.  Grasshoppers  in  California. 

143.  California  Peach-Tree  Borer. 

144.  The  Peach- Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their   Hybrids. 

149.  California  Sugar  Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl  Cholera. 

157.  Commercial  Fertilizers. 

158.  California  Olive  Oil ;  its  Manufacture. 

CIRCULARS. 

No.  1.  Texas  Fever.  No.  8.  Laboratory     Method     of     Water 

2.  Blackleg.  Analysis. 

3.  Hog  Cholera.  9.  Asparagus  Rust. 

4.  Anthrax.  10.  Reading     Course     in     Economic 

5.  Contagious  Abortion  in  Cows.  Entomology. 

6.  Methods  of  Physical  and  Chem-  11.  Fumigation  Practice. 

ical  Soil  Analysis.  12.     Silk  Culture. 

7.  Remedies   for   Insects. 

Copies  may  be  had  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


